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Organometallic Syntheses of Thiophene-Quinoline Combinations.

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There are compound as well as simple functional groups,
and from the former are derived semiarenologous and
arenologous groups (Table 2). Although many semiarenologous groups are known and, in the case of the azolides
[(3) of Table 21, are recognized as having functional
activity, the arenologous type is as good as uninvestigated
(cf. c2* 81).
Table 3. Urea syntheses as example of the application of the arenology
principle to reactions.
normal
2 NH3 + C l - &
0C l
4
::
H,N-C-NH,
Table 2. Examples of compound functional groups and arenologs.
Normal
Semiarenologous
Arenologous
The arenofunctional groups mentioned above are monocyclic 6 n-electron systems. It is apparent that corresponding bicyclic Ion- (e.g. quinoline, cf. Ref. [8]) or tricyclic
14n-electron systems could fullfil analogous functions.
The relationship between 6n-arenofunctional and normal
functional groups is similar to that between 14n-, Ion-,
and 6 n-arenofunctional groups.
::
-C-Hal
The bond energy between the arenofunctional groups in
(2) (the CC bond) is probably higher (cf. Ref. [2]) than
that between the functional groups of the acid amide
group ( I ) , and this could be advantageous for arenologous
Nylon [e.g. ( 4 ) ] and Perlon types, whose synthesis is
therefore being studiedI7].
L
J"
The chemical reactions that functional groups undergo
can be divided into three types (Table 3). So far only the
synthesis of "arenologous urea" ('5) from 2,6-dichloropyridine has been carried outf2],but as yet not that starting
from (6).
[I] Protophanes and Polyarenes, Part 4.-Part 3 : [2].
[Z] T h . Kauffmann, E. Wienhofer, and A . Woltermann, Angew. Chem.
83,796 (1971); Angew. Chem. internat. Edit. 10,741 (1971).
[3] A . Albert: Heterocyclic Chemistry. University of London, The
Athlone Press, 1959 ; Chemie der Heterocyclen. Verlag Chemie, Weinheim 1962.
[4] H . A . Staab, Angew. Chem. 74,407 (1962); Angew. Chem. internat.
Edit. I , 351 (1962).
151 T h . Kauffmann, G. Beissner, W. Sahm, and A . Woltermann, Angew.
Chem. 82, 815 (1970); Angew. Chem. internat. Edit. 9, 808 (1970).
[6] T h . Kauffmonn, G. Beissner, and R . Maibaum, Angew. Chem. 83,
795 (1971); Angew. Chem. internat. Edit. 10,740 (1971).
[7] J . Jackisch, Proposed dissertation, Universitat Miinster, 1972.
[S] T h . Kauffmann, J . Jackisch, H.-J. Streitberger, and E . Wienhofer.
Angew. Chem. 83, 799 (1971); Angew. Chem. internat. Edit. 10, 744
(1971).
[9] Strong Lewis acids presumably can be used for activation in several
cases.
[lo] This order is not intended to state that the two types of functional
groups correspond best when the heteroatoms correspond.
[ I l l In the sense of column 3 of Table 2, i.e. not semiarenologous.
[I21 The pyridine nucleus reacts with nucleophiles analogously to a
carbonyl group with good negative leaving groups. Only with bad
negative leaving groups (aldehydes, ketones) does the carbonyl group
behave differently (addition instead of substitution).
744
Received: July 5,1971 [Z 473d IE]
German version: Angew. Chem. 83,798 (1971)
Organometallic Syntheses of Thiophene-Quinoline
Combinations['l[**]
By Thomas Kaufmann, Jorg Jackisch,
Hans-Joachim Streitberger, and Ekkehard Wienhofer"'
Interaction of 2-thienylmagnesium iodide and pyridine in
xylene at 130°Cgives 2- and 4-(2-thienyl)pyridine(together
4%13]),but treatment with 2-thienylmagnesiumbromide in
ether at 35°C
or with 2-lithiothiophene in THF at
60°C (5%)[51affords only the 4-isomer, for which chelate
formation in the 2-adduct (1) is held responsible.
0S
Li
l-..
..
(I)
--3
2-Substitution
LY
[*I
Prof. Dr. Th Kauffmann, DipLChem. J. Jackisch,
H. J. Streitberger, and E. Wienhofer
Organisch-Chemisches Institut der Universitat
44 Miinster, OrlCans-Ring 23 (Germany)
This work was supported by the Deutsche Forschungsgemeinschaft and the Fonds der Chemischen Industrie.
[**I
Angew. Chem. internat. Edit.
Vol. 10 (1971) / N o . 10
However, treating 2-lithiothiophene with quinoline at 20°C
by Giiman's methodf6]leads only to 2-(2-thienyl)quinoline
(2) (38%), indicating steric hindrance of 4-addition by the
peri-hydrogen atom of the quinoline. In the following
reactions of the quinoline system with 2-lithiothiophene
derivatives substitution is also only at the 2-position.
cxpqwa
S
(4)
a-
%QcJUa-0
s
s
'Re
The yield of 2-(2-thienyl)quinoline (2) could be raised to
75% by causing the components to react at 45°C [2 h in
ether/n-hexane (2: I)], the 2-position of the thienyl group
being provided by an analogous synthesis from 2-chloroquinoline instead of quinoline and by NMR spectroscopy.
The lithium compoundc6]obtained therefrom by n-butyllithium [yield 33% on the basis of the yield of alcohol
(m. p. 221 "C) resulting from treatment with benzophenone]
reacts with quinoline to give the trisarene ( 3 ) and with
CuCl, to give the tetrakisarene (4). As shown in the formula
scheme and Table, compound ( 4 ) was accessible in higher
yield by reaction of 2,2'-bithiophene and 2 mol of n-butyllithium with subsequent treatment with quinoline. The
analogous reaction with one mol of the two reagents gave
the trisarene (6) as main product.
Analogous methods afford compounds (8) and ( 9 ) which
are homologs of ( 4 ) and (6) and of interest as starting
materials for protophane syntheses[71.Their preparation
is possible because 1,2-di-(2-thienyl)ethane(7) (an "arenologous diamine", cf. Ref. [2]) is metalated by n-butyl-
Reaction
Treatment [a] of
the metalated [b]
product
Yield
Product
Color
(%)
M. p.
("C)
2 h, 35°C
3 h, 35°C
14
14
189-190
250-251
Yellow
Yellowishred
1 h,
I h,
2 h,
2 h,
37
40 rc1
57
24 [dl
142
189
87
Yellow
Pale yellow
Pale yellow
35°C
35°C
35°C
35°C
[a] Solvent: diethyl ether (+ ca. 10% of n-hexane introduced with nbutyllithium); in the reaction (2) + ( 4 ) a n additional 10% of THF.
[b] Metalation always with n-butyllithium at 0°C (30 min).
[c] 26% of ( 4 ) formed as by-product.
[d] Yield calculated on n-butyllithium which was used in excess to
suppress the formation of (8).
Angew. Chem. internat. Edit. 1 Vof. I0 (1971) / No. 10
lithium in ether/n-hexane (9 :1)only in the thiophene rings
and not on the aliphatic bridge. The yield of (8) is considerably better than that of ( 9 ) since the monolithium
derivative from (7) is in equilibrium with the dilithium
compound and the unmetalated compound.
The Table records the reaction conditions, yields, and
properties of the apparently new compounds prepared,
their structures being proved by elemental analyses, mass
and NMR spectra, and the method of their preparation.
Received: July 5, 1971 [Z 473e I€]
German version: Angew. Chem. 83,799 (1971)
[l] Protophanes and Polyarenes, Part 5.-Part 4: [2]
[2] Th. Kaufmann,Angew. Chem. 83,798 (1971); Angew. Chem. internat. Edit. 10,743 (1971).
[3] H . Wynberg, ?: J . uan Bergen, and R. M. Kelfog, J. Org. Chem. 34,
3175 (1969).
[4] K . Kahmann, H . Sigel, and H.'Erienmryer, Helv. Chim. Acta 47,
1754 (1964).
[S] A . Woltermann and Th. Kaufmann, experiments 1971.
[6] H . Gifman and D.A Shirley, J. Amer. Chem. SOC.71, 1870 (1949).
[7] Th. Kuufmann, G. Beissner, and R. Maibaum, Angew. Chem. 83,
795 (1971); Angew. Chem. internat. Edit. 10,740 (1971).
Direct Transformationof the Second Excited
Singlet State of Benzene into Dewar-Benzene
By D.Bryce-Smith, A. Gilbert, and D.A . Robinson"]
We have found that the S, state of benzene (but not the S,
state) can isomerize directly into Dewar-benzene (bicyclo[2.2.0]hexa-2,5-diene) by a symmetry allowed process
which appears to provide the first example of a non-dissociative photochemical reaction from an upper excited
singlet state.
Irradiation of liquid benzene under nitrogen at 254 nm
populates the S, state ('B,u) and thence the T, state ( 3 B , ~ ) ,
and gives the benzene isomers fulvene['I and benzvaleneF2],
but no trace of Dewar-benzene. On the other hand, this
latter isomer is among those formed by irradiation of
liquid benzene over the 160-210 nm range, a process
which directly populates both the S, (lB,u) and S, ('E,u)
states of benzenef3].The interesting question arises whether
Dewar-benzene is being formed by a hitherto unknown
type of direct isomerization of the S, and/or S, states: such
transformations would be symmetry allowed, as wouId
that of the T , state, but would not be thus allowed from
the S, or So statesc4].It was therefore desirable to identify
more precisely the state of benzene which transforms into
Dewar-benzene.
['I
Prof. D. Bryce-Smith, Dr. A. Gilbert, and Dr. D. A. Robinson
Department of Chemistry, University of Reading
Whiteknights Park, Reading R G 6 2 AD (England)
745
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organometallic, synthese, thiophene, quinolinic, combinations
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